Reduce the fraction 140/210 to its simplest form, if possible.?

Reducing fractions means dividing the numerator (top) and denominator (bottom), by the same number, and producing a whole number (you could reduce to decimals, but this isn't normally accepted as being reduced or simplified).

Generally I would suggest first trying to divide by 10. If this won't work, try 9, then 8, and so on. Remember you need to divide top AND bottom by the SAME number.

In you're case you can divide 140 by 10 AND 210 by 10, and be left with: 14 / 21

Now do the process again: we can't use 10, since that gives 1.4 / 2.1. 9 won't work since neither is divisible by 9. 8 won't work either. 7 does work however, since 14 / 7 = 2, and 21 / 7 = 3

So our final answer is 2/3

You can also attempt the division on a calculator and rewrite that as a fraction if you're able. For example, 140/210 will give you 0.666666666 on a calculator. This is 2/3. 400 / 1000 will give you 0.4, which is equal to 2/5, since 2/5 = 0.4 as well. This process requires practice though, and generally only works for simple easy fractions. It also requires some memorization, and normally only works for any fraction where the denominator is 2 through 9 :/

Note for larger numbers you can use the first method, but use 100 -> 90, 80, etc.

Another fine method is dividing by 2 first, then 3, etc. These really come from knowing your times tables and finding common factors between numerator and denominator.

They both end with 0 so you can divide them both by 10 easily. That gets you to 14/21.
Both of those are multiples of 7, so divide them by 7, leaving you at 2/3.

2/3

divide top by 10 (= 14) so divide bottom by 10 (= 21)

7 will divide into (14) and (21).. which gives 2 on top and 3 on the bottom.

Alternatively you could have divided both top and bottom by 70, giving again 2 over 3.

And always check afterwards, by multiplying the end fraction(=2 3rds) by 70 top+bottom too.

And that should equal what you started with, which was 140 over 210.